A charged particle generically refers to a “particle having an electric charge,” including an ion in which an element in the periodic table is in a certain positive or negative charge state, and an electron. The charged particle also includes a particle of a compound, protein and the like having a large number of constituent molecules.
First, the background art of the induced voltage control device and method of controlling the device will be described. Synchrotrons are classified into an rf synchrotron and a synchrotron making use of induction cells. The rf synchrotron is a circular accelerator for causing charged particles, such as protons, injected into a vacuum chamber by an injector to circulate on a design orbit in the vacuum duct for a charged particle beam to circulate in, using an rf cavity 4, while accelerating the particles by applying an rf acceleration voltage synchronized with the magnetic excitation pattern of a bending electromagnet composing the rf synchrotron and ensuring strong focusing.
On the other hand, the synchrotron making use of induction cells differs in the acceleration method from the rf synchrotron and is a circular accelerator that performs charged particle acceleration by applying an induced voltage using the induction cell. FIG. 13 shows the principle of proton beam acceleration using an rf cavity and FIG. 14 shows the principle of proton beam acceleration using induction cells.
FIG. 13(A) shows a condition in which injected protons are circulating on the design orbit 2 of an rf synchrotron 21 as several bunches 3. Each bunch 3, as the result of being subjected to the application of an rf acceleration voltage 21a in synchronization with the magnetic excitation pattern when reaching the rf cavity 4, is accelerated to a predetermined energy level.
FIG. 13(B) shows the correlation between the bunches 3 and the rf acceleration voltage 21a applied thereto. The axis of abscissa “t” represents a temporal change in the rf cavity 4, whereas the axis of ordinate “v” represents an rf acceleration voltage. “Vofs” is an rf acceleration voltage 21b necessary for the acceleration of the bunches 3 calculated from the gradient (rate of temporal change) of the magnetic excitation pattern of the bending electromagnet at a moment of acceleration.
The bunches 3 is subjected by the rf cavity 4 to the application of “Vofs” (rf acceleration voltage 21b) which is calculated from the gradient (rate of temporal change) of the magnetic excitation pattern of the bending electromagnet and is necessary for acceleration. The rf acceleration voltage 21a has both the function to provide a voltage necessary to accelerate the bunches 3 and the confinement function to prevent the bunches 3 from dispersing in the propagating axis direction thereof.
In particular, the confinement function may, in some cases, be referred to as phase stability. The above-described two functions are always required when accelerating a charged particle beam using the rf synchrotron 21. The time duration in which the rf acceleration voltage 21a has the above-described two functions is limited, however. It has been heretofore known that the time durations shaded in FIG. 13(B) are not available for acceleration.
Note here that phase stability refers to a state in which individual charged particles receive focusing forces in an propagating axis direction caused by the rf acceleration voltage 21a, to turn into the bunches 3 and circulate within the rf synchrotron 21 while moving back and forth in the propagating axis direction.
In addition, the bunches 3 refer to groups of charged particles that undergo phase stabilization to circulate on the design orbit 2.
FIG. 14(A) shows a condition in which a bunch 3 (hereinafter referred to as a super-bunch 3b) having a time span several to ten times the length of a charged particle beam accelerated using a existing rf synchrotron 21, thus amounting to as long as one microsecond, is accelerated by a synchrotron 22 making use of induction cells. In this case, there is the need to dispose two or more induction cells of the same structure on the design orbit 2 for the proton beam of the synchrotron 22 making use of induction cells to circulate in.
One of these two induction cells (hereinafter referred to as the induction cell for confinement 23) provides a confinement function for confining the super-bunch 3b, whereas the other induction cell (hereinafter referred to as the induction cell for acceleration 6) provides the function to apply a voltage necessary to accelerate the super-bunch 3b in synchronization with the magnetic excitation pattern of the bending electromagnet. Using these two induction cells, there are provided the confinement function and the acceleration function necessary to operate the synchrotron 22. These two induction cells can also provide the same functions to a normal bunch 3.
Note here that the induction cells in principle have the same structure as that of an induction cell for liner induction accelerators heretofore constructed. The induction cells have a double structure composed of an inner cylinder and an outer cylinder, wherein a magnetic material is inserted into the outer cylinder to create an inductance. Part of the inner cylinder connected to the vacuum chamber, through which the charged particle beam passes, is made of an insulator such as ceramics.
When a pulse voltage is applied from a DC power supply to a primary electric circuit surrounding the magnetic material, a primary current (core current) flows through a primary conductor. This primary current causes magnetic fluxes to be produced around the primary conductor, thereby exciting the magnetic material surrounded by the primary conductor.
As a result, the density of fluxes penetrating the magnetic material in a toroidal shape increases with time. At this time, an induction electric field is produced across an insulating material in secondary insulated portions, which are the both ends of the conductor's inner cylinder, according to Faraday's induction law. This induction electric field serves as an acceleration electric field. A portion where the acceleration electric field is produced is referred to as an acceleration gap. Accordingly, the induction cells may be said to be one-to-one transformers.
By connecting a switching electric power supply for generating pulse voltages to the primary electric circuits of the induction cells and externally turning on and off the switching electric power supply, it is possible to freely control the generation of acceleration electric fields.
FIG. 14(B) shows a condition in which the super-bunch 3b is confined and accelerated by the induction cells. The axis of abscissa “t” denotes the timing of induced voltage generation based on the time when the super-bunch 3b reaches the induction cell for confinement 23 and is also a time length (hereinafter referred to as a charging timing) during which an induced voltage is applied.
Note that the generation timing and the charging timing of an induced voltage applied to the induction cell for acceleration 6 are shifted by half of a revolution time period 24 from those of the induction cell for confinement 23. The axis of ordinate “v” denotes an induced voltage value. “Vofs” denotes an acceleration voltage 9k which is calculated from the gradient (rate of temporal change) of a magnetic excitation pattern at a moment of acceleration and is necessary for the acceleration of the super-bunch 3.
Note here that an induced voltage refers to a voltage to be applied to charged particles by the induction cells. An induced voltage applied by the induction cell for confinement 23 is referred to as a barrier voltage. A barrier voltage applied to the head of a charged particle beam is particularly referred to as a negative barrier voltage 23a and a barrier voltage applied to the tail of a charged particle beam is particularly referred to as a positive barrier voltage 23b. The same applies to a case wherein the charged particles are the super-bunch 3b. 
As a result, it is possible to provide phase stability to the bunches 3 in the induction cell for confinement 23, as in the rf cavity 4. However, the induction cell for acceleration 6 is needed separately since a charged particle beam cannot be accelerated with one induction cell alone.
An induced voltage applied by the induction cell for acceleration 6 is referred to as an induced voltage for acceleration. In addition, an induced voltage applied to the whole of a charged particle beam is particularly referred to as an acceleration voltage 9a and an induced voltage applied in order to prevent the magnetic excitation of the induction cell for acceleration 6 is particularly referred to as a reset voltage 9b. The same applies to a case wherein the charged particles are the super-bunch 3b. 
Note that the reset voltage 9b corresponds to the positive barrier voltage 23b in the induction cell for confinement 23. Whereas the positive barrier voltage 23b is applied to the tail of the bunch 3 to confine the bunch 3, the reset voltage 9b is applied only to prevent magnetic core from saturating, in a time duration (time duration shown by a shaded area) in which no charged particle beams exist.
Note here that confinement is a function required since charged particles composing a charged particle beam always have a variation of kinetic energy. The variation of kinetic energy causes a difference in the time at which a charged particle beam reaches the same position after making one circuit of the design orbit 2. This time difference increases as the charged particle beam repeats circuiting unless confinement is carried out, thus causing the charged particle beam to disperse across the design orbit 2.
When the negative barrier voltage 23a and the positive barrier voltage 23b are made to be respectively applied to the head and the tail of the charged particle beam, charged particles over-energized and therefore leading in revolution lose energy and become under-energized due to the negative barrier voltage 23a, whereas charged particles under-energized and therefore lagging in revolution gain energy and become over-energized due to the positive barrier voltage 23b. 
Accordingly, a particle leading in revolution lags and, conversely, a particle lagging in revolution leads. As a result, it is possible to localize a charged particle beam in a certain region of the propagating axis direction thereof. This series of actions is referred to as the confinement of charged particle beams.
Consequently, the functionality of the induction cell for confinement 23 is equivalent to the confinement function separated from among the functions of the existing rf cavity 4.
The term “for confinement” means that the induction cell in question has the function to shrink a charged particle beam injected from an injection device to the synchrotron 22 making use of induction cells to a bunch 3 having a certain length, so that the beam can be induction-accelerated by another induction cell by applying a predetermined barrier voltage provided thereby and change the beam to a charged particle beam of various lengths, and the function to provide the bunch 3 being accelerated with phase stability.
The term “for acceleration” means that the induction cell in question has the function to provide an induced voltage for acceleration to the whole of the bunch 3 after the bunch 3 is formed.
FIG. 14(C) shows only the confinement function of the induction cell for confinement 23, whereas FIG. 14(D) shows only the acceleration function of the induction cell for acceleration 6. The axis of abscissa “t(a)” denotes the generation timing and the charging timing of a barrier voltage based on the time when the super-bunch 3b reaches the induction cell for confinement 23. The axis of ordinate “t(b)” denotes the generation timing and the charging timing of an induced voltage for acceleration 9 based on the time when the super-bunch 3b reaches the induction cell for acceleration 6. Other reference numerals and symbols are the same as those of FIG. 14(B).
As shown in the Journal of the Physical Society of Japan, vol. 59, No. 9 (2004) pp. 601-610, which is Non-patent Document 1, in the case of acceleration by the synchrotron 22 making use of induction cells, it is in principle possible to use the rest of time for acceleration except the time of charging the reset voltage 9b (time duration shown by a shaded area). It is considered to be possible to also accelerate the super-bunch 3b, which has been in principle not possible with the rf synchrotron 21, by dramatically increasing the time duration available for acceleration as described above.
As described above, it is now possible to confine proton beams also with a barrier voltage, as with the rf acceleration voltage 21a. On the other hand, another accelerating device is needed in order to accelerate the proton beams and such an accelerating device may be comprised of the rf cavity 4 as long as protons or other charged particles are concerned. Alternatively, the accelerating device may be configured so as to confine proton beams with the rf cavity 4 and accelerate the proton beams with the induced voltage 9.
As shown in Phys. Rev. Lett. Vol. 94, No. 144801-4 (2005), which is Non-patent Document 2, the inventor et al. have already succeeded in accelerating a proton beam injected at a kinetic energy of 500 million electron volts up to 8 billion electron volts by installing the induction cell for acceleration 6 in the proton rf synchrotron 21 (hereinafter referred to as the 12 GeVPS) of High Energy Accelerator Research Organization (hereinafter referred to as KEK) and applying the induced voltage for acceleration 9 generated at regular time intervals by combining the rf cavity 4 and the induction cell for acceleration 6.
Note here that one electron volt is given by multiplying the volt, which is the unit of voltage, by the unit charge of an electron. One electron volt equals 1.602×10−19 joule.
Next, the background art of the charged particle beam orbit control device and its control method will be described.
Synchrotrons are classified into an rf synchrotron and a synchrotron making use of induction cells. The rf synchrotron is a circular accelerator for causing charged particles, such as protons, injected into a vacuum chamber by an injector to circulate on a design orbit in the vacuum chamber for a charged particle beam to circulate in, using an rf cavity, while accelerating the particles by applying an rf acceleration voltage synchronized with the magnetic excitation pattern of a bending electromagnet composing the rf synchrotron and maintaining the beam revolution orbit.
On the other hand, the synchrotron making use of induction cells differs in the acceleration method from the rf synchrotron and is a circular accelerator that performs acceleration by applying an induced voltage to a charged particle beam using an induction cell.
FIG. 22 shows the principle of accelerating charged particle beams using induction cells and the types of induced voltages. The induction cells are classified into an induction cell for confinement designed to confine charged particle beams in the propagating axis direction thereof (hereinafter referred to as an induction cell for confinement) and an induction cell for applying an induced voltage designed to accelerate the charged particle beam in the propagating axis direction of ions (hereinafter referred to as an induction cell for acceleration).
Note that in some cases an rf cavity may be used in place of the induction cell for confinement, in order to confine charged particle beams in the propagating axis direction of ions thereof.
FIG. 22(A) shows a condition in which a charged particle beam is confined by an induction cell for confinement. An induced voltage applied to the charged particle beam by the induction cell for confinement is referred to as a barrier voltage 122.
In particular, an induced voltage opposite in direction to the propagating axis direction of a group of charged particles (hereinafter referred to as the bunch 103) and applied to the head of this charged particle beam is referred to as a negative barrier voltage 122a and an induced voltage the same in direction as the propagating axis direction of the group of charged particles and applied to the tail of this charged particle beam is referred to as a positive barrier voltage 122b. These voltages are intended to provide the charged particle beam with the phase stability, as with a existing rf cavity.
Note that the axis of abscissa “t” represents temporal change in the induction cell for acceleration and the axis of ordinate “v” represents a barrier voltage value (the value of an induced voltage for acceleration in FIG. 22(B)) to be applied.
FIG. 22(B) shows a condition in which a charged particle beam is accelerated by the induction cell for acceleration. An induced voltage applied to the charged particle beam by the induction cell for acceleration is referred to as an induced voltage for acceleration 108. In particular, the induced voltage 108 for acceleration applied to the whole of a bunch 103 and necessary to accelerate the charged particle beam in the propagating axis direction thereof is referred to as an acceleration voltage 108a and the value thereof is referred to as an acceleration voltage amplitude 108i. 
In addition, the induced voltage for acceleration 108, which is applied when the bunch 103 does not exist in the induction cell for acceleration and is heteropolar to the acceleration voltage 108a, is referred to as a reset voltage 108b. This reset voltage 108b is intended to prevent the magnetic excitation of the induction cell for acceleration.
With the induced voltage for acceleration 108 and the barrier voltage 122, it is considered possible to accelerate not only protons and specific charged particles but also any charged particles, as in a existing rf synchrotron, using a single unit of a circular accelerator, up to an arbitrary energy level permitted by the magnetic flux density of a bending electromagnet composing the synchrotron (hereinafter referred to as an arbitrary energy level).
Furthermore, as shown in the Journal of the Physical Society of Japan, vol. 59, No. 9 (2004) pp. 601-610, which is Non-patent Document 1, it is possible to also accelerate a bunch 103 (super-bunch) having a time span several to ten times the length of a charged particle beam accelerated using a existing rf synchrotron, thus amounting to as long as one microsecond, by using the induction cells. Accordingly, nuclear physics and high-energy physics experiments are considered to make a dramatic progress.
Note there that the induction cells mentioned above in principle have the same structure as that of an induction cell for liner induction accelerators heretofore constructed. The induction cells have a double structure composed of an inner cylinder and an outer cylinder, wherein a magnetic material is inserted into the outer cylinder to create an inductance. Part of the inner cylinder connected to the vacuum chamber, through which the charged particle beam passes, is made of an insulator such as ceramics.
When a pulse voltage is applied from a DC power supply to a primary electric circuit surrounding the magnetic material, a primary current (core current) flows through a primary conductor. This primary current causes magnetic fluxes to be produced around the primary conductor, thereby exciting the magnetic material surrounded by the primary conductor.
As a result, the density of fluxes penetrating the magnetic material in a toroidal shape increases with time. At this time, an induction electric field is produced across an insulating material in secondary insulated portions, which are the both ends of the conductor's inner cylinder, according to Faraday's induction law. This induction electric field serves as an acceleration electric field. A portion where the acceleration electric field is produced is referred to as an acceleration gap. Accordingly, the induction cells may be said to be one-to-one transformers.
By connecting a switching electric power supply for generating pulse voltages to the primary electric circuits of the induction cells and externally turning on and off the switching electric power supply, it is possible to freely control the generation of acceleration electric fields.
Now, the switching electric power supply and the equivalent electric circuit diagram of the induction cell for acceleration will be described (FIG. 23). The equivalent electric circuit diagram 123 of an induction accelerating device for acceleration can be represented as a circuit wherein a switching electric power supply 105a that constantly receives power from a DC power supply 105b is connected to an induction cell for acceleration 107 through a transmission line. The induction cell for acceleration 107 is represented as a parallel circuit of an inductance component L, a capacitance component C and a resistance component R. The voltage developing across the parallel circuit is an induced voltage 108 for acceleration that a bunch 103 senses.
The state of the circuit shown in FIG. 23 is such that a first switch 124a and a fourth switch 124d are turned on by a gate signal pattern 113a, a voltage charged to a bank capacitor 124 is applied to the induction cell for acceleration 107, and an acceleration voltage 108a for accelerating the bunch 103 to an acceleration gap 107a is present.
Next, the turned-on first switch 124a and fourth switch 124d are turned off and a second switch 124b and a third switch 124c are turned on by the gate signal pattern 113a, thus producing a reset voltage 108b opposite in direction to the induced voltage in the acceleration gap 107a and thereby resetting the magnetic excitation of the magnetic material of the induction cell for acceleration 107.
Then, the second switch 124b and the third switch 124c are turned off and the first switch 124a and the fourth switch 124d are turned on by the gate signal pattern 113a. As the result of such a series of switching actions as described above being repeated by the gate signal pattern 113a, it is possible to generate the induced voltage 108 for acceleration necessary to accelerate charged particle beams.
The gate signal pattern 113a is a signal for controlling the driving of the switching electric power supply 105a and is digitally controlled by an induction accelerating device for acceleration composed of a digital signal processor 112 and a pattern generator 113, according to the passage signal 109a of the bunch 103.
Note that the acceleration voltage 108a applied to the bunch 103 is equivalent to a value calculated from the product of a current value and a matching resistance 125 in the circuit. Consequently, it is possible to know the value of the applied acceleration voltage 108a by measuring the current value using an induced voltage monitor 126, which is an ammeter or the like.
As shown in Phys. Rev. Lett. Vol. 94, No. 144801-4 (2005), which is Non-patent Document 2, the inventor et al. have already succeeded in accelerating a proton beam injected at a kinetic energy of 500 million electron volts up to 8 billion electron volts by installing the induction cell for acceleration 107 in the proton rf synchrotron 21 (hereinafter referred to as the 12 GeVPS) of High Energy Accelerator Research Organization (hereinafter referred to as KEK) and applying the induced voltage 108 for acceleration generated at regular time intervals by combining the rf cavity and the induction cell for acceleration 107.
Note here that one electron volt is given by multiplying the volt, which is the unit of voltage, by the unit charge of an electron. One electron volt equals 1.602×10−19 joule.
Now, problems to be solved by the induced voltage control device and its control method will be described first. While it has been described earlier that the induced voltage for acceleration 9 necessary to accelerate a charged particle beam is determined by the gradient (rate of temporal change) of the magnetic excitation pattern 15 of a bending electromagnet, the rate of temporal change in the magnetic field temporally has a different value, depending on the magnetic excitation pattern. For this reason, a voltage to be applied to the charged particle beam must be temporally varied from the start to the end of acceleration of the charged particle beam.
Conventionally, there have been no devices for generating the induced voltage for acceleration 9 to be applied to charged particle beams and, therefore, there have been no methods of adjusting the induced voltage for acceleration. On the other hand, there has conventionally been a method of modulating the amplitude of a pulse voltage and the pulse width thereof general power supply devices which output commercial-frequency alternative current by modulated pulse voltage in order to adjust an output voltage. With the existing method, however, it is not possible to synchronize the induced voltage for acceleration 9 with a magnetic excitation pattern 15.
In order to obtain a stable output power of several tens of kilowatts necessary for a device for generating induced voltages (hereinafter referred to as an induction accelerating device), a large static capacitance (bank capacitor) must be loaded to the high-voltage charging portion of the switching electric power supply for determining the pulse voltage amplitude. Since the purpose of the charged voltage of this bank capacitor is to stabilize the pulse voltage output, the charged voltage cannot be varied at high speeds. Consequently, it is in reality not possible to have the pulse voltage amplitude controlled at high speeds.
Hence, the present invention is intended to solve the aforementioned problems. An object of the invention, therefore, is to provide a device capable of accelerating an arbitrary charged particle beam to an arbitrary energy level permitted by the magnetic flux density of a bending electromagnet composing the synchrotron making use of induction cells (hereinafter referred to as an arbitrary energy level) and its control method, by applying the required acceleration voltage 9a, even if it is a constant acceleration voltage provided by the induction cell for acceleration 6, in synchronization with every magnetic excitation pattern, including the nonlinear excitation region thereof, immediately after the bunch 3 is injected into a synchrotron making use of induction cells.
Note that the content of Non-patent Document 2 is a report that the inventor et al. were able to accelerate a proton beam using the constant acceleration voltage 9a applied at regular time intervals in the linear excitation region of a magnetic excitation pattern.
Next, problems to be solved by the charged particle beam orbit control device and its control method will be described. FIG. 24 shows the orbit of a charged particle beam and a condition in which the charged particle beam is confined in a horizontal direction by magnetic fields. A synchrotron maintains a bunch 103 on a design orbit 102 by means of magnetic flux density 103a provided by bending electromagnets composing the synchrotron.
In the absence of the magnetic flux density 103a provided by the bending electromagnet, the bunch 103 collides with the wall surfaces of a vacuum chamber due to a centrifugal force 103b that the charged particle beam has, and is lost. This magnetic flux density 103a varies with acceleration time. This variation is referred to as a magnetic excitation pattern (FIG. 19). This magnetic excitation pattern allows the revolution frequency band width of a charged particle beam to be uniquely determined once the type of charged particles, the acceleration energy level thereof, and the circumferential length of a circular accelerator are defined.
Consequently, the induced voltage for acceleration 108 must be applied, like an rf acceleration voltage, to the charged particle beam in synchronization with this magnetic excitation pattern, in order to accelerate the beam in the propagating axis direction thereof.
The orbit of a charged particle beam is not the vacuum chamber center 102a of the synchrotron, but is a design orbit 102 for the charged particle beam to circulate in situated either on the outside or on the inside of the vacuum chamber center 102a determined by the location of the bending electromagnet composing the synchrotron. Note that “ρ0” is an average radius 102d from the centroid of the circular accelerator to the central beam orbit in the vacuum chamber 102a. 
Note here that the term “synchronization” means that the acceleration voltage 108a is applied to the charged particle beam in conformity with a change in the magnetic excitation pattern, so that a balance is achieved between Lorentz force based on the magnetic flux density 103a of the bending electromagnet composing the synchrotron and the centrifugal force 103b that works outwardly by the acceleration of the charged particle beam.
However, the acceleration voltage 108i applied at each revolution of the bunch 103 is not constant but more or less increases or decreases. This stems from a variety of reasons, including that the charged voltage of a bank capacitor 124 deviates from the ideal value thereof.
If as a result, the acceleration voltage 108i actually applied is excessively lower than the acceleration voltage 108i ideal for synchronization with the magnetic excitation pattern, the charged particle beam deviates from the design orbit 102 toward the inside 102b thereof. On the other hand, if the acceleration voltage 108i actually applied is excessively higher than the ideal acceleration voltage 108i, the charged particle beam deviates from the design orbit 102 toward the outside 102c thereof.
In a existing rf synchrotron, it was possible to accelerate or decelerate a charged particle beam and maintain the beam on the design orbit 102 by shifting the phase of an rf voltage in an accelerating or decelerating direction.
In the induction cell for confinement, however, although it is possible to shift the time of generation of the barrier voltage 122, it is not possible to bring the bunch 103, which has deviated from the design orbit 102 toward the outside 102c, i.e., has become unable to synchronize with the magnetic excitation pattern, back on the design orbit 102.
Using a steering magnet or the like, an attempt has been made conventionally to correct an orbit for an actual proton beam to circulate in to the design orbit 102. However, correction using a steering magnet is intended to locally correct the orbit of the bunch 103 that has deviated from the design orbit 102.
Since the parameter “magnetic field strength” does not appear in the equation of beam acceleration, the time propagation of the revolution velocity 103c of the beam easily lost synchronization state with the predetermined magnetic excitation pattern. Accordingly, it is not possible to bring the bunch 103, whose energy has deviated from a designed value, back on the design orbit 102 by varying the magnetic flux density.
As a method for bringing the charged particle beam back on the design orbit 102, it is conceivable that the magnitude of the acceleration voltage 108i is changed. However, a device for generating the acceleration voltage 108i (hereinafter referred to as the induction accelerating device for acceleration) requires loading a large bank capacitor 124 (static capacitance) to the high-voltage charging portion of the switching electric power supply 105a for determining the pulse voltage amplitude, in order to obtain a stable output power of several tens of kilowatts necessary for the induction cell for acceleration 107.
Since the purpose of the charged voltage of this bank capacitor 124 is to stabilize the pulse voltage output, the charged voltage cannot be varied at high speeds. Consequently, it is in reality not possible to have the pulse voltage amplitude controlled at high speeds.
It is therefore not possible to largely vary the voltage value in a short time since the output voltage is uniquely determined once the DC power supply 105b and the bank capacitor 124 to be used are defined. For this reason, in a method of modulating the pulse voltage amplitude, it is not possible to synchronize the acceleration voltage 108a with the magnetic excitation pattern.
Alternatively, it is conceivable that an rf cavity is used concurrently as a cavity for controlling the orbit of the charged particle beam by its acceleration voltage. It is in reality impossible, however, to control the rf cavity's voltage to accelerate an arbitrary charged particle within an arbitrary energy range by a single synchrotron.
This is because the revolution frequency from a point in time immediately after injection to the end of acceleration becomes extremely low for particularly heavy charged particles, whereas the revolution frequency of the charged particle beam needs to be synchronized with the magnetic excitation pattern.
In every rf cavity, an rf voltage is generated based on the principle of resonance between inductance and capacitance. On the other hand, there are limits on the frequency of the rf acceleration voltage that can be generated since the frequency of the rf voltage is proportional to approximately −½ power of an inductance. As a result, it is not possible for the rf cavity to apply a required rf acceleration voltage.
In addition, if “Z/A”, which is a ratio of the charge number “Z” to the mass number “A” of charged particles, differs in a synchrotron making use of an rf cavity, the frequency change during acceleration itself must be changed for reasons of limits on the principle in which high frequencies are used.
Unless errors in the above-described acceleration voltage 108i to be applied are eliminated in a synchrotron making use of induction cells, the charged particle beam deviates to the outside 102c from the design orbit 102 due to the centrifugal force 103b that the charged particle beam has, once the charged particle beam receives the acceleration voltage 108i higher than the required acceleration voltage 108i. Thus it is no longer possible to accelerate the charged particle beam.
Hence, the present invention is intended to solve the aforementioned problems. An object of the invention, therefore, is to provide an orbit control device for modulating the orbital deviations of the charged particle beam by modulating in real time the equivalent acceleration voltage 108i (hereinafter referred to as the pulse density (FIG. 21)) corresponding to the ideal acceleration voltage 108i and applying the acceleration voltage 108a based on the corrected pulse density to the charged particle beam in a unit that collectively represents a specific number of revolutions of the charged particle beam and provides the acceleration voltage 108i equivalent to the ideal acceleration voltage 108i for a specific time period (hereinafter referred to as the control time block (FIG. 20)), and to provide a method of controlling the orbit control device.